When I enter fullscreen (whether it is borderless or exclusive), the framerate will usually drop almost by half. What is strange is that this only started happening until a couple of weeks ago. My PC is very capable of playing just about every game in HD resolution, I have tried using multiple Dolphin versions, I've tried setting the aspect ratio to auto or the native resolution of my monitor, and it the games only go back to full speed when clicking the Windows key to show the Start Menu, or exiting fullscreen.